Add brotli content-encoding filter.

net/filter/mock_filter_context.h

Index: net/filter/mock_filter_context.h
diff --git a/net/filter/mock_filter_context.h b/net/filter/mock_filter_context.h
index 33d41a6e53ee6880f5b9a82ded51f971c075284f..f7b40b7bdbfd896089d54f6dda2f30463c4ea75f 100644
--- a/net/filter/mock_filter_context.h
+++ b/net/filter/mock_filter_context.h
@@ -30,6 +30,9 @@ class MockFilterContext : public FilterContext {
   void SetSdchResponse(scoped_ptr<SdchManager::DictionarySet> handle) {
     dictionaries_handle_ = handle.Pass();
   }
+  void SetBrotliEnabled(bool is_brotli_enabled) {
+    is_brotli_enabled_ = is_brotli_enabled;
+  }
   URLRequestContext* GetModifiableURLRequestContext() const {
     return context_.get();
   }
@@ -66,6 +69,8 @@ class MockFilterContext : public FilterContext {
 
   const BoundNetLog& GetNetLog() const override;
 
+  bool IsBrotliEnabled() const override;
+
  private:
   std::string mime_type_;
   GURL gurl_;
@@ -76,6 +81,7 @@ class MockFilterContext : public FilterContext {
   int response_code_;
   scoped_ptr<URLRequestContext> context_;
   BoundNetLog net_log_;
+  bool is_brotli_enabled_;
 
   DISALLOW_COPY_AND_ASSIGN(MockFilterContext);
 };